Vitamin d - Fact Sheet by David Stache

What is vitamin D?

Vitamin D is a group of fat soluble vitamins which the body makes under the skin when you are exposed to sunlight. Vitamins are nutrients which help our body function, however Vitamin D is actually a hormone which we make in our body. Foods such as fish and eggs contain natural sources of Vitamin D and some dairy products are fortified with it too.

 

What does it do in my body?

Vitamin D is actually produced in the body from cholesterol, to do this however it needs UV light from sun exposure. As we live in Britain where even June can see rain and a summer feels like it only lasts 2 weeks in July it is fair to assume that although not deficient, most people probably do not have optimal levels. Vitamin D plays a vital role in the absorption of calcium and also helps to promote bone growth. Vitamin D deficiency has been linked to breast cancer, depression, weight gain, heart disease and prostate cancer, studies have shown although a lack of vitamin d did not cause these issues higher levels of vitamin d show a lower risk of disease. There are many claims and benefits of vitamin d, however it’s important to highlight that very few research studies have shown that solely vitamin d offers such wide ranging benefits, the key is an overall healthy balanced diet, of which optimum vitamin d are an important part of that. Vitamin D plays a role in helping calcium build strong bones in the body, which is why it is often added to dairy products, additionally it helps regulate the immune system as well as the neuromuscular system. It also plays a major role in the life cycle of human cells too through modulation of cell cycle proteins which decrease cell proliferation and increase cell differentiation.

 

What is the skins role in vitamin d?

Vitamin D is synthesized underneath the skin; this occurs when ultraviolet (UV) rays from the sunlight strike the skin. Following this2 enzymatic reactions are needed, the first one in the kidney and the second one in the kidney. once this happens, the body then has a usable source of Vitamin D.

 

What foods can I eat which contain vitamin d

As previously mentioned foods such as fish and eggs contain vitamin D, however the majority of foods which contain vitamin d are actually fortified with the vitamin, meaning the vitamin is added to the food and it is not naturally occurring within the food.

vitamin d which is consumed from food or supplement is absorbed in the small intestine, meaning bile from the liver, pancreatic secretions, stomach juices and health of the intestinal wall all have an influence over how much is absorbed. Therefore, gut conditions can reduce the absorption of vitamin D. 

 

Can I get too much vitamin D?

Vitamin D toxicity is incredibly rare, with very few cases reported or diagnosed. The threshold level has also not been established, however in this instance there has been a tolerable upper intake level researched, but even more confusingly, different research has set this at differing values. Some as low s 4000iu per day, others as high as 50000iu per day. The only reported cases where vitamin d toxicity involving the key indicator of hypocalcemia (elevated calcium levels in the blood) the dosage used has been in excess of 40000iu per day. Both the united states and Canada have set a safe upper limit of 4000iu per day, however it is generally agreed that a safe upper limit is 10000iu per day.

 

Why should I supplement with vitamin D?

As discussed there are many benefits from optimal levels of vitamin D and whilst it is important to note that vitamin d alone has not been shown to offer such wide and varied health benefits, it is fair to assume that living in the UK our vitamin d levels are unlikely to be at optimal levels and as a cheap supplement with plays a vital role in many cellular functions within the body, ensuring we’re at an optimal level through supplementation makes sense. Additionally, consuming enough from foods will mean you’re having to consume foods which are fortified, which are usually highly processed foods too. 

 

How much should I take per day?

Firstly, as vitamin d is fat soluble it should be taken with a meal, preferably one which contains fat as the fatty acid helps to transport it. The amount required does vary with each person, however as a general rule 5000iu per day is a good and safe point by which to start and will allow you to steadily reach optimal levels. It is also worth noting that as a fat soluble vitamin levels will build up slowly and we can store the inactive properties for some time.